Dinosaurs were thriving until asteroid struck, research suggests

Dating of rock formation in New Mexico casts doubt on theory that species was already in decline

Dinosaurs would not have become extinct had it not been for a catastrophic asteroid strike, researchers have said, challenging the idea the animals were already in decline.

About 66m years ago, during the late Cretaceous period, a huge space rock crashed into Earth, triggering a mass extinction that wiped out all dinosaurs except birds. However, some experts have argued the dinosaurs were already in decline.